Boosted engines are in common use in which air is compressed by an air compressor powered by either a turbo positioned in the engine exhaust or the engine crankshaft. Compression will increase air temperature. Consequently the compressed air is often routed through a heat exchanger commonly referred to as a charge air cooler before entering the engine air intake. Under high ambient air humidity conditions condensate will form in the heat exchanger. In some prior approaches condensate is always routed into the engine exhaust and in other prior approaches condensate is always routed into the engine air intake.
The inventors herein have recognized that always routing the condensate to either the exhaust or the air intake regardless of engine operating conditions and regardless of whether there are contaminants in the condensate has led to undesirable engine or catalyst operation. For example, always routing condensate to the air intake may result in rough engine operation. And always routing condensate to the exhaust upstream of a catalyst at low or moderate engine loads may result in undesired catalyst cooling. Further, if engine oil is present in the condensate routing the condensate to the catalyst may result in undesired catalyst operation. Further, throwing away the engine oil by dumping it into the engine exhaust downstream of the catalyst is undesirable from an emissions or efficiency perspective.
The inventors herein have solved these issues by a method, in one example, which comprises: routing air through a heat exchanger and into combustion chambers of the engine; forming condensate in the heat exchanger; and routing the condensate to either the combustion chambers or a position in the engine exhaust based upon both the type of contaminate detected within the condensate and operating parameters of the engine or the catalyst. For example, in one embodiment a CAC may incorporate a specific geometry designed into the inlet tanks in order to separate condensate from the air path, and further direct the condensate to either the combustion chambers or a position in the engine exhaust based upon the type of contaminate present. In one particular aspect, when the engine is operating at a high load and engine oil is not present in the contaminate, the condensate is routed into the engine exhaust upstream of the catalyst to cool the catalyst. In another example, when the engine is operating at a high load and engine oil is present in the contaminate, the condensate is routed into the engine combustion chambers to combust the oil without contaminating the catalyst. In still another aspect, engine power is reduced when engine coolant is in the condensate to allow the operator to drive to a safe place without harming the engine.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings. It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.